Thermionic tube



Dec. 3, 1929.

M. os os 1,738,390

THERMIONIC TUBE Fil'ed March 7, 1927 INVENTOR MENDEL osuos BY AT RNEY Patented Dec. 3, 1929 UNITED STATES PATENT? OFFICE MENDEL OSNOS, OF BERLIN, GERMANY, ASSIGINOR T0 GESELLSCHAFT F'U'R DRAHT- LOSE TELEGRAPHIE M. B. H., OF BERLIN, GERMANY, A. CORPORATION OF GERMANY THERMIONIG TUBE Application filed March 7, 1927, Serial No. 173,612, and in Germany March 12, 1926.

parts contained therein must be caused to inc'andesce in order to expel them of the last traces of occluded gases. German Patent #204,749 discloses a method adapted thereto, in which the metallic part to be heated is incandesced by eddy currents set up therein by means of a primary coil outside of the vessel and surrounding or enveloping the latter. The metal piece has a core serving to intensify the magnetic field which core consists of iron wires or strips. This iron core makes it feasible to obtain sufficient heating of the metal sheet even with low frequency, medium frequency, and even some high frequency current. However, this method is unsuited for exhausting cathode tubes since an iron core in this case would be hard to mount, let alone the near impossibility of removing it after the exhaust hasbeen terminated.

It has now been suggested to compensate for the extremely great reduction in-field intensity due to the absence of iron cores by a correspondingly great increase in the frequency. In this manner, in order to heat the anode, it is possible to produce eddy currents by the use of very high frequencies say in the order of magnitude of (10).

The object of the present invention is to disclose other means to obviate the difficulty attendant upon the use of iron cores.

This is arrivedat by having the iron or the ferro-magnetic material disposed on the anode itself. This is accomplished by coating the plate with a very thin ferro-magnetic layer, such layer being produced thereon by any of the well known methods, for instance by electrolysis, spraying and the like.

If the anode is of a cylindrical shape, better results are obtained by only covering the inner surface with the said ferro-magnetic layer. Such a thin ferro-magnetic coating makes it possible to insure sufficient heating of the plate even with low, medium or high frequencies.

The accompanying drawing shows diagrammatically one embodiment of my invention.

means.

is well known in the art and is here shownonly as illustrative of a class of devices which may be advantageously treated in accordance with my invention. The structural features of the device need not therefore be described here in great detail.

According to my invention, conductive parts within the envelope 2 and particularly the anodes 3 are heated by a magnetic field induced by a winding 1, which may he slipped over the device in any convenient way. The winding 1 is connected to a source of current, not shown, by the conductors 6 and 7 The inner portion of said anode is coated with some ferro-magnetic or similar substance 4. Such a layer of substance can be produced thereon by any well known method, f o1' 1nstance, by electrolysis, spraying or similar It can therefore be seen that the ferro-magnetic substance serves to intensity the magnetic field much the same as an iron core would, and therefore make it feaslble to obtain suflicient heating of the metal, even with low frequency, medium frequency and high frequency current.

Having thus described my inventlon, what I desire to protect by'Letters Patent is as follows 1. The method of heating the anode of a thermionic tube which comprises coverlng the faces of the anode with a layer of ferromagnetic material and inducing eddy currents within said anode.

2. The method of heating the anode of a thermionic tube which consists in covering the anode with a thin layer of ferro-magnetic material and inducing eddy currents sufficiently to heat said anode. a 3. The method of heating a cyllndrlcal anode of a thermionic tube which consists in placing a thin layer of ferro-magnet c substance on the inside thereof and sub ect1 ng said anode through an outside agency to induced currents.

4. The method of heating the anode of a thermionic tube for the purpose of exhausting said tube which consists in covering such anode with a thin layer of some ferro-mag-. netic substance and thereafter inducing eddy currents upon said anode.

5. A vacuum tube comprising an anode, a

5 grid electrode and a filament, sa1d anode having thereon a thin layer of a ferro-magnetic substance.

6. A method of. removing gases from electrically conducting masses which comprises coating said masses with a thin layer of some ferro-magnetic substance, reducing the gasemasses and inducing eddy-currents within said masses.

MENDEL ossos. 

